Electrode assembly for catheter system including interlinked struts

ABSTRACT

The present disclosure provides ablation catheter systems and electrode assemblies and electrode baskets for use in the ablation catheter systems that include an interlinked diamond configuration formed from a plurality of strut assemblies. Each strut assembly includes one or more struts that are manufactured from a thermoplastic or metallic material. The interlinked diamond configuration facilitates reducing an overall length of the electrode assembly. Further, the interlinked diamond configuration facilitates expanding and contracting the struts simultaneously and by the same amount.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to provisional application Ser. No.61/896,344, filed Oct. 28, 2013, the entire specification of which isincorporated herein.

A. FIELD OF THE DISCLOSURE

The present disclosure relates generally to a catheter system for use ina human body, and more particularly to catheter system including anelectrode assembly an interlinked diamond configuration.

B. BACKGROUND ART

Catheter systems are well known in the art for use in medicalprocedures, such as diagnostic, therapeutic and ablative procedures.Typical catheter systems generally include an elongate catheterextending from a handle. A physician manipulates the catheter throughthe patient's vasculature to an intended site within the patient. Thecatheter typically carries one or more working components, such aselectrodes and thermocouples, or other diagnostic, therapeutic orablative devices for carrying out the procedures. One or more controlsor actuators may be provided on the handle for selectively adjusting oneor more characteristics of the working components.

One particular example of a multi-electrode catheter system is anablative catheter system in which the working component is amulti-electrode assembly carried at the distal end of a flexiblecatheter. A control wire generally extends within the catheter from themulti-electrode assembly to the handle to operatively connect themulti-electrode assembly to an actuator on the handle. Manipulating theactuator acts on the control wire to configure the multi-electrodeassembly into a desired configuration for carrying out the ablativeprocedure. For example, in one such ablative catheter system made by St.Jude Medical, Inc. under the trade name EnligHTN, the multi-electrodeassembly is an electrode assembly in the general form of an electrodebasket. The electrode basket generally includes a number of struts,wherein each strut may include one or two electrodes. In at least someknown catheter systems, however, the electrode basket is relativelylong, and different struts may expand and collapse at different times,and by different amounts, which may interfere with ablation processes.

BRIEF SUMMARY OF THE DISCLOSURE

In one embodiment, the present disclosure is directed to an electrodeassembly for an ablation catheter system. The electrode assemblyincludes a first strut assembly comprising a first distal end and afirst proximal end, and a second strut assembly comprising a seconddistal end and a second proximal end, wherein the second distal end ispositioned between the first distal end and the first proximal end suchthat the first and second strut assemblies form an interlinkedconfiguration.

In another embodiment, the present disclosure is directed to an ablationcatheter system. The ablation catheter system includes a handle, anelongate shaft extending from the handle, and an electrode assemblycarried by the shaft and having a longitudinal axis, a proximal end anda distal end. The electrode assembly includes a first strut assemblycomprising a first distal end and a first proximal end, and a secondstrut assembly comprising a second distal end and a second proximal end,wherein the second distal end is positioned between the first distal endand the first proximal end such that the first and second strutassemblies form an interlinked configuration.

In another embodiment, the present disclosure is directed a method forassembling an electrode assembly for an ablation catheter system. Themethod includes forming a first strut assembly that includes a firstdistal end and a first proximal end, forming a second strut assemblythat includes a second distal end and a second proximal end, andinterlinking the first and second strut assemblies such that the seconddistal end is positioned between the first distal end and the firstproximal end.

The foregoing and other aspects, features, details, utilities andadvantages of the present disclosure will be apparent from reading thefollowing description and claims, and from reviewing the accompanyingdrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a catheter systemincluding a handle, a catheter and an electrode assembly having multipleelectrodes, with the electrode assembly being in a collapsedconfiguration.

FIG. 2 is a side elevation of the catheter system of FIG. 1, with theelectrode assembly being in an expanded configuration resulting fromrotation of a rotatable actuator.

FIGS. 3A-3D illustrate various stages of a manufacturing process forstruts for an electrode basket as described herein.

FIG. 4 illustrates a partially flattened thermoplastic tube includingembedded electrodes and fold lines for preparing struts for an electrodebasket as described herein.

FIG. 5 illustrates the formation of struts from thermoplastic tubes toform an interlinked diamond electrode basket.

FIG. 6 illustrates the formation of struts from a thermoplastic tube.

FIG. 7 illustrates the formation of an interlinked diamond electrodebasket including a center lumen and guidewire in accordance with oneembodiment of the present disclosure.

FIG. 8 illustrates an interlinked diamond electrode basket withthermoplastic struts in an expanded configuration in accordance with thepresent disclosure.

FIG. 9 illustrates an interlinked diamond electrode basket withthermoplastic struts in a collapsed configuration in accordance with thepresent disclosure.

FIG. 10 illustrates an interlinked diamond electrode basket withthermoplastic struts in an expanded configuration in accordance with thepresent disclosure.

FIG. 11 illustrates an interlinked diamond electrode basket withthermoplastic struts in a collapsed configuration in accordance with thepresent disclosure.

FIG. 12 illustrates an interlinked diamond electrode basket withmetallic struts in an expanded configuration in accordance with thepresent disclosure.

FIG. 13 illustrates an interlinked diamond electrode basket withmetallic struts in a collapsed configuration in accordance with thepresent disclosure.

FIG. 14 illustrates an interlinked diamond electrode basket withmetallic struts in an expanded configuration in accordance with thepresent disclosure.

FIG. 15 illustrates an interlinked diamond electrode basket withmetallic struts in a collapsed configuration in accordance with thepresent disclosure.

Corresponding reference characters indicate corresponding partsthroughout the several views of the drawings.

DETAILED DESCRIPTION OF THE DISCLOSURE

The present disclosure provides ablation catheter systems and electrodeassemblies and electrode baskets for use in the ablation cathetersystems that include an interlinked diamond configuration formed from aplurality of strut assemblies. Each strut assembly includes one or morestruts that are manufactured from a thermoplastic or metallic material.The interlinked diamond configuration facilitates reducing an overalllength of the electrode assembly. Further, the interlinked diamondconfiguration facilitates expanding and contracting the strutssimultaneously and by the same amount.

In many embodiments, the electrode assembly includes struts that aremanufactured from heat-treated thermoplastic material. Alternatively,the struts may be manufactured from a metallic material, such asnitinol. The electrode basket described in detail herein generallyincludes struts that are configured in the electrode assembly to operateas two diamond shapes in an interlinked formation. It should beunderstood, however, that an electrode basket including the strutsdescribed herein may include two, three, four or more diamonds or othershapes, including but not limited to oblong, oval, hexagonal, circular,trapezoidal or the like, in accordance with the present disclosure. Thediamonds present in the formation may be of the same size, or may be ofdifferent sizes (such as for a tapered design for tapered vessels).Further, although described in detail below with respect to two diamondsin an interlinking configuration, it is understood that more than twodiamonds may be used in any interlinking configuration without departingfrom the scope of the present disclosure. For instance, the electrodeassembly may include four diamond, or other shape, electrode strutassemblies arranged such that a first and second electrode strutassembly are interlinked with one another and a third and fourthelectrode strut assembly are interlinked with one another, wherein thefirst interlinking pair is separate from the second interlinking pair.In another embodiment, the electrode strut assemblies may be arrangedsuch that more than two electrode strut assemblies are interlinked in aserial arrangement or such that at least two electrode strut assembliesare interlinked with each other but separate from additional electrodestrut assemblies. In many embodiments, the struts in an interlinkeddiamond formation are set in an expanded or collapsed configurationusing an internal or central lumen within an outer catheter connected toa catheter handle. The struts may be constructed using traditional heatpresses or irons, or may in some embodiments be produced by an injectionmolding and/or extrusion process.

By configuring the strut assemblies in an interlinked diamondconfiguration, the overall length of the electrode assembly is reduced,increasing flexibility and maneuverability of the electrode assemblythrough anatomical structures. Further, in the interlinked diamondconfiguration described herein, to expand or collapse the electrodeassembly, a central lumen travels a relatively short distance ascompared to at least some known electrode assemblies. Moreover, thestruts in the interlinked diamond configuration are relatively short androbust. Additionally, using thermoplastic struts in the interlinkeddiamond configuration described herein may simplify the manufacturingprocess and reduce costs, while improving overall reliability andstrength of the strut. Because the thermoplastic materials that may beused to construct the struts are self-insulating, there is no need touse a polymer or thermoplastic coating to be electrically insulatedduring operation, which further reduces costs and improves efficiency.

In some embodiments described herein, the struts include one or moreelectrodes on the exterior of the struts; that is, the electrodeencircles the exterior of the strut with the electrode wiring beingrouted through or around the strut to a catheter handle or other device.In other embodiments, the struts include one or more embeddedelectrodes; that is, the electrode is partially embedded within thestrut such that only a portion of the electrode protrudes from the strutand contacts tissue during an ablation procedure, with the electrodewiring being routed through the strut to a catheter handle or otherdevice. Combinations of external and embedded electrodes are also withinthe scope of the present disclosure.

Referring now to the drawings, and in particular to FIGS. 1 and 2, aconventional catheter system 2 is shown by way of background andreference. Catheter system 2 includes a flexible catheter 4, a handle 6to which flexible catheter 4 is connected, and a conductor assembly 8for electrically connecting catheter system 2 to a suitable power supply(not shown). As one example, catheter system 2 illustrated and describedherein is suitably constructed for use as an ablation system, such as arenal or heart ablation system. More particularly, illustrated cathetersystem 2 is a multi-electrode renal denervation system. One example ofsuch a catheter system 2 is currently made by St. Jude Medical, Inc.under the trade name EnligHTN. General operation of a multi-electroderenal denervation system is known to those of skill in the art and isnot described further herein except to the extent necessary to describethe present embodiments. It is also understood that catheter system 2may be used for any other suitable treatment or purpose withoutdeparting from the scope of this disclosure. Additionally, whilecatheter system 2 is illustrated and described herein as includingflexible catheter 4, catheter system 2 may further include othercomponents used, for example, to guide flexible catheter 4 into thepatient—such as, without limitation, a relatively more rigid guidecatheter (not shown) or guide wire (not shown).

Flexible catheter 4 includes an elongate, flexible hollow shaft 10connected to handle 6 at or near a proximal or rear end of the cathetershaft (not shown because it is hidden by a connector at the front end ofhandle 6), and an electrode assembly 12 disposed at or near a distal orfront end 14 of flexible hollow shaft 10. Electrode assembly 12 includesproximal end 13 and distal end 15. It is understood, however, thatelectrode assembly 12 may be disposed anywhere along flexible hollowcatheter shaft 10 intermediate the proximal end and the distal end 14thereof without departing from the scope of this disclosure. As usedherein, the terms proximal and front, and distal and rear, are used withreference to the orientation of catheter system 2 illustrated in thevarious drawings and for the purpose of describing the variousembodiments set forth herein, and are not intended as limiting thecatheter system and related components to having any particularorientation upon assembly or during operation thereof. In particular,the terms proximal and rear refer to a longitudinal position that isrelatively nearer to handle 6 while the terms distal and front refer toa longitudinal position that is relatively farther from handle 6.

Illustrated electrode assembly 12 is in the form of what may be referredto as an electrode basket and includes struts 20, and is suitablyconfigurable between a collapsed configuration (FIG. 1) for maneuveringand positioning the electrode assembly in the patient, and an expandedconfiguration (FIG. 2) for operation of the electrode assembly toperform a desired procedure such as an ablation procedure. An annular(e.g., ring-shaped) actuator 16 is mounted on handle 6 for rotationrelative thereto and is operatively connected to electrode assembly 12for selectively configuring the electrode assembly between its collapsedand expanded configurations. It is understood that another suitableactuator (e.g., slide, push button, lever, etc.) may be used instead ofrotating actuator 16 to selectively configure electrode assembly 12without departing from the scope of this disclosure. In someembodiments, electrode assembly 12 may be selectively adjustable betweenan infinite number of configurations (e.g., degrees of expansion)between its collapsed and expanded configurations using actuator 16.

A control line, such as a suitable cable or pull wire 18 extends fromelectrode assembly 12 within hollow catheter shaft 10 and into thehandle 6 for operative connection with the actuator to therebyoperatively connect the actuator 16 with electrode assembly 12. In someembodiments two or more pull wires, cables or other suitable controllines or tubes may be used for selectively configuring electrodeassembly 12. It is also understood that control line 18 may be anysuitable control line other than a pull wire, such as a cable, string,tie, compression member or other suitable control to operatively connectelectrode assembly 12 to actuator 16. A suitable electrical wire bundle(not shown) also extends through hollow catheter shaft 10 from handle 6to electrode assembly 12 to deliver power to, and receive feedback from,electrode assembly 12.

As noted above, the present disclosure includes struts for an electrodeassembly or electrode basket that are generally arranged in aninterlinked diamond configuration. In many embodiments, the electrodeassembly includes struts that are manufactured from heat-treatedthermoplastic material. Alternatively, the struts may be manufacturedfrom a metallic material, such as nitinol.

As used herein, the term “thermoplastic material” refers to a materialthat becomes plastic upon heating providing flow properties and thathardens upon cooling and is able to repeat these procedures. Thethermoplastic material used to construct the struts as disclosed hereinis generally in the shape of a tube, although other shapes andconfigurations are within the scope of the present disclosure. Suitablethermoplastic materials for constructing the electrode basket struts asdescribed herein include, for example, polystyrene, polyvinyl chloride,ethylene vinyl acetate, polyurethanes (urethane-based materials), nylon,polyether block amides (Pebax®), and the like. Other heat settableplastics or superplastics are also suitable and known to those ofordinary skill in the art. Particularly desirable thermoplasticmaterials include Pebax® polyether block amides.

The thermoplastic material used to construct the struts for theelectrode basket has a suitable hardness and rigidity such that theresulting strut is sufficiently strong and durable when utilized in theelectrode basket. In many embodiments, the thermoplastic material willhave a durometer value of from 30 Shore A to 100 Shore A, including from40 Shore A to 90 Shore A, including from 50 Shore A to 80 Shore A,including form 60 Shore A to 75 Shore A, including about 72 Shore A.Additionally, the thermoplastic material used to construct the strutsfor the electrode basket may have a wall thickness of from about 0.001inches (about 0.00254 centimeters) to about 0.01 inches (about 0.0254centimeters), including from about 0.001 inches (about 0.0025centimeters) to about 0.008 inches (about 0.0203 centimeters), includingfrom about 0.002 inches (about 0.0051 centimeters) to about 0.007 inches(about 0.0178 centimeters), including from about 0.003 inches (about0.0076 centimeters) to about 0.006 inches (about 0.0152 centimeters),including about 0.005 inches (about 0.0127 centimeters). The innerdiameter and outer diameter of the thermoplastic tube are not criticaland may be selected based on the desired size of the strut to beconstructed and the desired electrical components to be used.

Once a suitable thermoplastic material is selected for constructing thestruts, a thermoplastic tube 22 (or other thermoplastic configuration),as shown in FIG. 3A, may be heat pressed at a suitable temperature(i.e., a temperature slightly above the melting point of thethermoplastic material) to produce a thermoplastic tube 24, as shown inFIG. 3B, that has been at least partially flattened such that it is nolonger circular. Other heating and pressing/flattening operations inaddition to, or in place of the heat pressing, are within the scope ofthe present disclosure and may be suitable to flatten the thermoplastictube. Thermoplastic tube 22 is not completely flattened and meltedtogether to form a solid substrate, but rather is partially flattened toa desired degree to close the thermoplastic tube from about 30% to about90%, including from about 40% to about 90%, including from about 50% toabout 90%, including from about 60% to about 90%, including from about70% to about 90%, including from about 70% to about 85%, including about80% to about 85% such that it is not completely closed off and meltedtogether. Thermoplastic tube 22 is not completely closed off and sealedin order to allow electrical wiring, such as electrical wiring for anelectrode and/or a thermocouple (or other electric components such assensors and the like), to be routed through flattened thermoplastic tube24 to another part of a catheter system, including to the catheterhandle.

Once thermoplastic tube 22 has been flattened to the desired degree, oneor more electrodes and/or thermocouples or other electronic devices orsensors may be introduced into or onto the thermoplastic tube to be usedto form the struts in an electrode basket for a catheter system asdescribed herein. In many embodiments, a single thermoplastic tube maybe used to construct a plurality of struts for the electrode basket. Forexample, as described herein, in some embodiments a first thermoplastictube is used to construct a first set of struts that form a first strutassembly, and a second thermoplastic tube is used to construct a secondset of struts that form a second strut assembly, wherein the first andsecond strut assemblies form an interlinked diamond configuration.

Each strut may include one, two, or more electrodes, each of which mayhave an internal thermocouple. In many embodiments, the electrode willbe a platinum electrode that includes an internal thermocouple. Ofcourse, electrode baskets formed with more than two diamonds and more orless than four electrodes are within the scope of the presentdisclosure, as well as struts formed from more than one thermoplastictube.

In one illustrated example, and now referring now to FIG. 3C, there isshown partially flattened thermoplastic tube 24 including exteriorelectrodes 26 and 32, each of which encircle the exterior of flattenedthermoplastic tube 24. Further shown is electrode wiring 36 and 40running partially through the interior of flattened thermoplastic tube24. Electrode wiring 36 and 40 is connected to electrodes 26 and 32respectively, via holes (not shown as they are covered by theelectrodes) in flattened thermoplastic tube 24. The holes are introducedinto flattened thermoplastic tube 24 through one side of the tube toallow wiring for electrodes 26 and 32 (and any other electroniccomponents) using a drill or other suitable device to introduce a holethrough one side of the thermoplastic material. Alternatively, the holesmay be introduced into the thermoplastic tube prior to the flatteningprocess. In many embodiments where a thermoplastic tube is used to formthe struts, after the electrode or electrodes are introduced onto theexterior of the flattened tube and the wiring is run internally throughthe tube, the thermoplastic tube and electrodes will be subjected to asecond heating and flattening process to flatten and seal the electrodeor electrodes on the exterior of the flattened tube. The flattening andsealing process negates the need for any adhesive to secure the exteriorelectrode to the thermoplastic tube. In some embodiments, a small amountof plastic filler material, which may optionally be the material thatcomprises the thermoplastic tube, may be used to help fill and seal anyopenings or rough edges around the electrodes, or other electricalcomponents. One skilled in the art will recognize based on thedisclosure herein that any electrical or other wiring present could berouted in many other alternative ways without departing from the scopeof the present disclosure.

In another embodiment, after thermoplastic tube 22 has been partiallyflattened and one or more holes introduced into one side of the tube asnoted above, one or more electrodes may be introduced into, or embeddedinto, the hole or holes such that the electrode or electrodes arepartially contained within flattened thermoplastic tube 24 and onlypartially protrude from the hole in flattened thermoplastic tube 24.Referring now to FIG. 3D, there is shown flattened thermoplastic tube 24including embedded electrodes 42 and 48, and embedded electrode wiring50 and 56. Generally, embedded electrode wiring 50 and 56 will be fedthrough the holes in flattened thermoplastic tube 24 and then theelectrodes introduced into the holes such that approximately the bottomhalf or bottom two thirds of each of the electrode is located withinflattened thermoplastic tube 24 and the top half of the electrodesprotrude out of flattened thermoplastic tube 24. Once embeddedelectrodes 42 and 48 have been introduced into the holes in flattenedthermoplastic tube 24, in many embodiments it may be desirable to applyheat via a heat gun or other heating apparatus at the juncture of eachhole and the embedded electrode to soften and melt a small amount of thethermoplastic material such that upon cooling, the melted materialassumes the conformation of embedded electrodes 42 and 48 for a tight,smooth fit and finish. In some embodiments, a small amount of plasticfiller material, which may be the material that comprises thethermoplastic tube, may be used to help fill and seal any openings orrough edges around the embedded electrodes, or other electricalcomponents.

When the thermoplastic strut includes one or more embedded electrodes asdescribed above, the energy transfer from the electrode and into thetissue being ablated may be more efficient and thus reduce proceduretime as energy delivered to the electrode is introduced directly intothe tissue only; that is, because no portion of the electrode iscontacting the blood in the vessel receiving the ablation procedure asthe electrode is only contacting tissue when positioned and energized,the energy loss is significantly minimized or eliminated and efficiencyis increased.

Once the thermoplastic strut including the electrodes, whether internal,external, or a combination of both, has been constructed, it may beutilized to form a portion of an interlinked diamond strut configurationincluding at least two diamonds for an electrode basket for use in theablation system described above. The struts disclosed and describedherein are suitable for use in ablation systems that use a pull wireconfiguration to open and close the electrode basket (in such systemswhere guide catheters as known in the art are used to guide theelectrode basket to a target site), as well as ablations systems thatinclude a guide wire (over the wire-type systems) and use a centrallumen to open and close the electrode basket. Although further describedherein in combination with embedded electrodes and over-the wiresystems, all further disclosure is equally applicable to embodimentsincluding exterior electrodes and/or pull wire systems.

Once the thermoplastic tube has been fitted with the electrodes, twofold lines may be introduced onto the thermoplastic tube (generally inthe center region) to assist in folding the thermoplastic tube ontoitself for making the struts using two folds. The folds may occur at anyangle that allows the desired conformation of the thermoplastic tube tobe obtained; that is, when the thermoplastic tube is folded onto itselfas described herein using the fold lines, the exact angle of folding maybe any angle suitable for properly positioning the folded sections ofthe thermoplastic tube for further processing including for example, 20degrees, or even 30 degrees, or even 40 degrees, or even 50 degrees, oreven 60 degrees or even 70 degrees or even 80 degrees or even 90degrees.

Referring now to FIG. 4, there is shown flattened thermoplastic tube 24including embedded electrodes 42 and 48 and corresponding embeddedelectrode wires 50 and 56, and further including fold lines 58 and 60.Fold lines 58 and 60 are introduced onto flattened thermoplastic tube 24using a heated iron or other flat heated surface to score thethermoplastic material such that the thermoplastic material will easilyfold upon the line in the desired area. Also shown FIG. 4 is hole 62,which is drilled through flattened thermoplastic tube 24 such that amandrel may be inserted therethrough later in the manufacturing processas described below.

Additionally, one or more optional but desirable living hinges may beintroduced onto flattened thermoplastic tube 24 to assist the formedstrut in bending and flexing in a desirable manner, in a predeterminedlocation, upon use in the electrode basket. Suitable living hinges aretypically thinned or cut into a desired material (such as the flattenedthermoplastic tube) to allow the rigid material on either side to bendalong the line of the hinge in a predictable and repeatable desiredmanner. Living hinges generally have very little friction and wear andmay be desirable due their ease of manufacturing as discussed below incombination with the benefits they provide. In another embodiment, whenpresent, the living hinges may be mechanical-type hinges.

When employed, living hinges will generally be introduced on both sidesof the electrode to assist in the bending of the strut about theelectrode. Referring now to FIG. 5, living hinges 51 and 53 areintroduced onto flattened thermoplastic tube 24 on both sides ofembedded electrode 42 to assist in the bending of the strut upon use.Additional living hinges 63 and 65 are also shown in FIG. 5 aboutembedded electrodes 48. Similar to fold lines 58 and 60 described above,the living hinges may be introduced onto flattened thermoplastic tube 24using a heated iron or other flat heating surface to score thethermoplastic material.

As shown in FIG. 5, a second thermoplastic tube 70 is formedsubstantially similar to thermoplastic tube 24. Thermoplastic tube 70includes embedded electrodes 72 and 74, and corresponding embeddedelectrode wires 76 and 78. Further, on thermoplastic tube 70, fold lines80 and 82 are formed about a hole 84, living hinges 90 and 92 are formedon both sides of embedded electrode 72, and living hinges 94 and 96 areformed on both sides of embedded electrode 74.

As shown in FIG. 5, to form the electrode assembly, a mandrel 64 isinserted through holes 62 and 84, and flattened thermoplastic tubes 24and 70 are folded onto themselves along fold lines 58, 60, 80, and 82 atapproximately 90 degrees. When folded, thermoplastic tube 24 forms afirst strut 100 and a second strut 102, and thermoplastic tube 70 formsa third strut 104 and a fourth strut 106. With struts 100, 102, 104, and106 formed, embedded electrodes 42 and 48 are generally aligned, andembedded electrodes 72 and 74 are generally aligned. Mandrels are knownin the art, and a suitable mandrel 64 may be a Teflon® coated rod suchthat the mandrel may be removed at the end of the manufacturing processwithout adhering to any of the thermoplastic or other material used inthe construction. As shown in FIG. 5, third and fourth struts 104 and106 are oriented at approximately 90 degrees relative to first andsecond struts 100 and 102 about a longitudinal axis of mandrel 64. It isunderstood, however, that third and fourth struts 104 and 106 may beoriented at any other angle to first and second struts 100 and 102 andstill be within the scope of the present disclosure.

Referring now to FIGS. 6 and 7, folding thermoplastic tube 24 to formfirst and second struts 100 and 102 creates a first strut assembly 110.First strut assembly 110 includes a first distal end 112 and a firstproximal end 114. Specifically, first distal end 112 is formed at hole62, and first proximal end 114 is formed by ends 116 and 118 ofthermoplastic tube 24. As shown in FIG. 7, ends 116 and 118 are coupledtogether at first proximal end 114. Ends 116 and 118 may be coupled toone another by melting and bonding ends 116 and 118.

After first and second struts strut 100 and 102 are formed, an optionalactivation stop (not show in FIGS. 6 and 7) may be introduced overmandrel 64. The activation stop may be included to ensure that uponexpansion of first strut assembly 110, first and second struts 100 and102 cannot become positioned such that the diamond shape of first strutassembly 110 extends too far and ultimately collapses onto itself. Thatis, the activation stop provides an optional mechanism to prevent theaccidental over-opening of first strut assembly 110 and undesirableself-collapse from which recovery may be difficult. The activation stopmay be constructed of any thermoplastic or similar material, and isdesirably constructed of the material utilized for the thermoplastictube.

To couple ends 116 and 118, in some embodiments, heat shrink material(not shown) is introduced between ends 116 and 118. The heat shrinkmaterial will have a melting point higher than the thermoplasticmaterial used to construct first strut assembly 110 such that upon theapplication of heat to the heat shrink material, the underlyingthermoplastic material will melt and flow while the heat shrink materialremains solid to hold the materials in place. When the heat isdiscontinued, ends 116 and 118 will be bonded together, and the heatshrink material may be cut away with a suitable cutting member, such asa razor blade.

A second strut assembly 120 is formed substantially similar to firststrut assembly 110. Specifically, folding thermoplastic tube 70 to formthird and fourth struts 104 and 106 creates second strut assembly 120having a second distal end 122 and a second proximal end 124. Forclarity, second strut assembly 120 is not shown in FIG. 6, and is shownonly as a dashed outline in FIG. 7. As described herein, in oneembodiment, second strut assembly 120 is oriented at approximately 90degrees relative to first strut assembly 110 about a longitudinal axisof mandrel 64. It is understood, however, that second strut assembly 120may be oriented at any angle relative to first strut assembly 100 andstill be within the scope of the present disclosure. As shown in FIG. 7,first strut assembly 110 and second strut assembly 120 form aninterlinked diamond configuration. Specifically, second distal end 122is positioned between first distal end 112 and first proximal end 114.Similarly, first proximal end 114 is positioned between second distalend 122 and second proximal end 124.

First proximal end 114 and second proximal end 124 are mated togetherwith an outside catheter member 130, which may be connected to thecatheter handle described above for use during an ablation procedure.The outside catheter 130, which may include a central lumen andguidewire as described hereinbelow, may be comprised of a braidedmaterial of sufficient strength and known in the art such that torqueand stress may be applied to the outside catheter during use without theoutside catheter failing. For example, the outside catheter may becomprised of a polyester block amide (Pebax®) material that is reflowedwith a Teflon liner. The outside catheter will have an inner diameterand an outer diameter suitably sized and configured to accommodate acentral lumen, guidewire, or other components known to those of ordinaryskill in the art. For example, the outside catheter may have an outsidediameter of about 0.060 inches (about 0.152 centimeters) and an internaldiameter of about 0.040 inches (about 0.102 centimeters).

Referring now to FIG. 7, there is shown outside catheter 130, into whichmandrel 64 is introduced. Electrode wires 50, 56, 76, and 78 are alsorouted into outside catheter 130. Once mandrel 64 is inserted intooutside catheter 130, first proximal end 114 and second proximal end 124are joined to outside catheter 130 using, for example, a heat shrinkmaterial (not shown). The heat shrink material will have a melting pointhigher than the thermoplastic material used to construct first andsecond strut assemblies 110 and 120, such that the underlyingthermoplastic material will melt and flow while the heat shrink materialremains solid to hold the materials in place. Heat shrink materials forbonding thermoplastic materials are well known in the art and suitableheat shrink materials are commercially available. Heat is applied to theheat shrink material to cause first proximal end 114 and second proximalend 124 to melt and bond with outside catheter 130 such that first andsecond strut assemblies 110 and 120 become bonded to and intimate with,outside catheter 130. Once the melting and bonding is complete, the heatshrink material may be cut away.

After first and second strut assemblies 110 and 120 are bonded tooutside catheter 130, mandrel 64 is removed from the electrode assemblyand a central lumen 140, which includes a bead 142, and a guidewire 144,is inserted in place of mandrel 64 through holes 62 and 84 and intooutside catheter 130, as shown in FIG. 7. In other suitable embodiments,such as when a guide catheter system is utilized, guidewire 144 may beomitted. Wires from electrodes 42, 48, 72, and 74 (and/or other optionalelectrical wires) are routed between outside catheter 130 and centrallumen 140 to the handle or other component of the ablation system asdescribed above.

FIG. 8 illustrates one embodiment of an electrode assembly 800 in anexpanded configuration, and FIG. 9 illustrates electrode assembly 800 ina collapsed configuration. Electrode assembly 800 may be formed, forexample, by the manufacturing process described above. Alternatively,electrode assembly 800 may be formed using any manufacturing processthat enables electrode assembly 800 to function as described herein.Electrodes 42, 48, 72, and 74 are not shown in FIGS. 8 and 9.

Central lumen 140, shown in FIGS. 7 and 8, may be operatively connectedto a handle (not shown in FIGS. 8 and 9) as described herein andutilized to configure first and second strut assemblies 110 and 120 inan expanded or collapsed configuration during an ablation procedure.Central lumen 140 may, for example, be constructed of a braided meshmaterial that has sufficient column strength, torqueability, anddurability to open and close the struts as described herein. In oneexample, the central lumen may be constructed of a braided meshpolyimide material and may have an outer diameter of about 0.0025 inches(about 0.0064 centimeters) and an inner diameter of about 0.0020 inches(about 0.0051 centimeters).

Bead 142 (shown in FIG. 7) is optionally constructed of a radiopaquematerial, such as platinum or other radiopaque materials known in theart, to act as a radiopaque marker during insertion of the assembly intothe patient's body. Once central lumen 140, guidewire 144, and a shortpiece of extension tubing 123 are positioned, heat is applied about thecircumference of distal ends of struts 104 and 106 along with tube 123to melt and flow second distal end 122 to central lumen 140. After heatshrink material is removed, first and second struts 100 and 102, bead142, extension 123, and central lumen 140 are bonded. Because centrallumen 140 is bonded to first and second strut assemblies 110 and 120,when central lumen 140 is pulled or moved toward the handle of acatheter as described herein, the struts 100, 102, 104, and 106 arepulled into an expanded formation to open and form an expandedinterlinked diamond formation, as illustrated in FIG. 8. Specifically,pulling central lumen 140 toward the handle of a catheter causes firstdistal end 112 to move towards first proximal end 114, pushingelectrodes 42 and 48 outward and away from one another. Similarly,pulling central lumen 140 toward the handle of a catheter causes seconddistal end 122 to move towards second proximal end 124, pushingelectrodes 72 and 74 outward and away from one another. By reversing thedirection of force on central lumen 140, the struts 100, 102, 104, and106 return to a collapsed configuration as shown in FIG. 9.

As shown in FIGS. 8 and 9, first strut assembly 110 is oriented atapproximately 90 degrees with respect to second strut assembly 120. Thatis, first strut assembly 110 expands and contracts in a first plane, andsecond strut assembly 120 expands and contracts in a second plane thatis substantially orthogonal to the first plane. It is understood,however, that first and second strut assemblies 110 and 120 may beoriented at any angle to one another and still be within the scope ofthe instant disclosure. Further, as explained above, second distal end122 is positioned between first distal end 112 and first proximal end114, and first proximal end 114 is positioned between second distal end122 and second proximal end 124.

As explained above, first distal end 112 and second distal end 122 arebonded to each other, and first proximal end 114 and second proximal end124 are bonded to each other. Accordingly, when pulling central lumen140, first and second strut assemblies 110 and 120 expand and collapsesimultaneously and by the same amount. Moreover, in the embodiment shownin FIGS. 8 and 9, as discussed above, first strut assembly 110 includesan activation stop 810 that facilitates preventing overexpansion offirst strut assembly 110.

FIG. 10 illustrates another embodiment of an electrode assembly 1000 inan expanded configuration, and FIG. 11 illustrates electrode assembly1000 in a collapsed configuration. Electrode 48 of second strut 100 andelectrode 74 of fourth strut 106 are shown in FIGS. 10 and 11.

As shown in FIGS. 10 and 11, electrode 48 and electrode 74 are offset bya distance, D, along a longitudinal axis of central lumen 140.Accordingly, in an expanded configuration, electrodes 42, 48, 72, and 74are not aligned in a circle, which may be advantageous for ablationpurposes. That is, electrodes 42, 48, 72, and 74 are not positioned inthe same concentric plane about electrode assembly 1000 so as todecrease the risk of a concentric lesion forming during an ablationprocedure if a spasm was to occur, and thus reducing the chance ofstenosis. Electrode assembly 1000 has an overall length, L, defined fromfirst distal end 112 to second proximal end 124. Notably, overall lengthL may be shorter than the length of at least some known electrodeassemblies, increasing flexibility and maneuverability of electrodeassembly 1000 through anatomical structures. For example, the length maybe reduced by about 40% as compared to at least some known electrodeassemblies.

Further, because of the reduced length L of electrode assembly 1000,central lumen 140 traverses a shorter distance (e.g., approximately halfthe distance) when expanding or collapsing electrode assembly 1000, ascompared to at least some known electrode assemblies. Moreover struts100, 102, 104, and 106 themselves are relatively short as compared tostruts in at least some known electrode assemblies, improving thestructural robustness (e.g., hoop strength) of electrode assembly 1000.

FIG. 12 illustrates another embodiment of an electrode assembly 1200 inan expanded configuration, and FIG. 13 illustrates electrode assembly1200 in a collapsed configuration. Unless otherwise described, electrodeassembly 1200 operates substantially similar to electrode assemblies 800and 1000. Electrode assembly 1200, unlike electrode assemblies 800 and1000, is formed using metallic materials instead of thermoplastics.

In electrode assembly 1200, struts 100, 102, 104, and 106 are eachformed from a metallic material, such as nitinol. Accordingly, insteadof melting distal and proximal ends 112, 114, 122, and 124 for bonding,distal and proximal ends 112, 114, 122, and 124 are bonded to form theinterlinked diamond configuration using a suitable adhesive. In general,components are coupled using reflow operations when thermoplastic strutsare utilized, and components are coupled using adhesive when metallicstruts are utilized. To maintain the distance D between electrodes onstruts 100 and 102 and electrodes on struts 104 and 106, proximal endsof struts 100 and 102 pass through a sleeve 1210, or collar, thatsurrounds central lumen 140. That is, sleeve 1210 prevents strutassemblies 110 and 120 from expanding and collapsing at the sameposition along central lumen 140.

FIG. 14 illustrates another embodiment of an electrode assembly 1400 inan expanded configuration, and FIG. 15 illustrates electrode assembly1400 in a collapsed configuration. Unless otherwise described, electrodeassembly 1400 operates substantially similar to electrode assembly 1200.Electrode assembly 1200, similar to electrode assembly 1200, is formedusing metallic materials.

In electrode assembly 1400, struts 100, 102, 104, and 106 are eachformed from a metallic material, such as nitinol. Each strut 100, 102,104, and 106 is substantially encased in insulating material 1410, butwith electrodes 42, 48, 72, and 74 exposed. Distal ends of struts 100and 102 are adhered to one another at bead 142. Similar to electrodeassembly 1200, a sleeve 1420 constrains proximal ends of struts 100 and102. Distal ends of struts 104 and 106 are gathered and adhered to oneanother in a cap 1420 that is further adhered to distal ends of struts100 and 102.

Although certain embodiments of this disclosure have been describedabove with a certain degree of particularity, those skilled in the artcould make numerous alterations to the disclosed embodiments withoutdeparting from the spirit or scope of this disclosure. All directionalreferences (e.g., upper, lower, upward, downward, left, right, leftward,rightward, top, bottom, above, below, vertical, horizontal, clockwise,and counterclockwise) are only used for identification purposes to aidthe reader's understanding of the present disclosure, and do not createlimitations, particularly as to the position, orientation, or use of thedisclosure. Joinder references (e.g., attached, coupled, connected, andthe like) are to be construed broadly and may include intermediatemembers between a connection of elements and relative movement betweenelements. As such, joinder references do not necessarily infer that twoelements are directly connected and in fixed relation to each other. Itis intended that all matter contained in the above description or shownin the accompanying drawings shall be interpreted as illustrative onlyand not limiting. Changes in detail or structure may be made withoutdeparting from the spirit of the disclosure as defined in the appendedclaims.

When introducing elements of the present disclosure or the preferredembodiment(s) thereof, the articles “a”, “an”, “the”, and “said” areintended to mean that there are one or more of the elements. The terms“comprising”, “including”, and “having” are intended to be inclusive andmean that there may be additional elements other than the listedelements.

As various changes could be made in the above constructions withoutdeparting from the scope of the disclosure, it is intended that allmatter contained in the above description or shown in the accompanyingdrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:
 1. An electrode assembly for an ablation cathetersystem, the electrode assembly comprising: a first strut assemblycomprising a first distal end and a first proximal end; and a secondstrut assembly comprising a second distal end and a second proximal end,wherein the second distal end is positioned between the first distal endand the first proximal end such that the first and second strutassemblies form an interlinked configuration.
 2. The electrode assemblyof claim 1 wherein the first strut assembly is configured to expand andcontract in a first plane, and wherein the second strut assembly isconfigured to expand and contract in a second plane different than thefirst plane.
 3. The electrode assembly of claim 1 wherein at least oneof the first and second strut assemblies is manufactured from athermoplastic material.
 4. The electrode assembly of claim 1 wherein atleast one of the first and second strut assemblies is manufactured froma metallic material.
 5. The electrode assembly of claim 1, wherein thefirst distal end is coupled to the second distal end, and wherein thefirst proximal end is coupled to the second proximal end such that thefirst and second strut assemblies are configured to expand and contractsimultaneously.
 6. The electrode assembly of claim 1 wherein the firststrut assembly comprises a first strut and a second strut each extendingbetween the first distal end and the first proximal end, and wherein thesecond strut assembly comprises a third strut and a fourth strut eachextending between the second distal end and the second proximal end. 7.The electrode assembly of claim 6 wherein each of the first, second,third, and fourth struts include at least one electrode.
 8. Theelectrode assembly of claim 1 further comprising a pull wire.
 9. Anablation catheter system comprising: a handle; an elongate shaftextending from the handle; and an electrode assembly carried by theshaft and having a longitudinal axis, a proximal end and a distal end,the electrode assembly comprising: a first strut assembly comprising afirst distal end and a first proximal end; and a second strut assemblycomprising a second distal end and a second proximal end, wherein thesecond distal end is positioned between the first distal end and thefirst proximal end such that the first and second strut assemblies forman interlinked configuration.
 10. The ablation catheter system of claim9 wherein the first strut assembly is configured to expand and contractin a first plane, and wherein the second strut assembly is configured toexpand and contract is a second plane different than the first plane.11. The ablation catheter system of claim 9 wherein at least one of thefirst and second strut assemblies is manufactured from a thermoplasticmaterial.
 12. The ablation catheter system of claim 9 wherein at leastone of the first and second strut assemblies is manufactured from ametallic material.
 13. The ablation catheter system of claim 9, whereinthe first distal end is coupled to the second distal end, and whereinthe first proximal end is coupled to the second proximal end such thatthe first and second strut assemblies are configured to expand andcontract simultaneously.
 14. The ablation catheter system of claim 9wherein the first strut assembly comprises a first strut and a secondstrut each extending between the first distal end and the first proximalend, and wherein the second strut assembly comprises a third strut and afourth strut each extending between the second distal end and the secondproximal end.
 15. The ablation catheter system of claim 9 wherein eachof the first, second, third, and fourth struts include at least oneelectrode.
 16. The ablation catheter system of claim 9 furthercomprising a guide wire.
 17. A method for assembling an electrodeassembly for an ablation catheter system, the method comprising: forminga first strut assembly that includes a first distal end and a firstproximal end; forming a second strut assembly that includes a seconddistal end and a second proximal end; and interlinking the first andsecond strut assemblies such that the second distal end is positionedbetween the first distal end and the first proximal end.
 18. The methodof claim 17, further comprising: bonding the first distal end to thesecond distal end; and bonding the first proximal end to the secondproximal end.
 19. The method of claim 17, wherein forming the first andsecond strut assemblies comprises forming the first and second strutassemblies from a thermoplastic material.
 20. The method of claim 17,wherein forming the first and second strut assemblies comprises formingthe first and second strut assemblies from a metallic material.